Implemented the schematic for the USB-C powered Wi‑Fi/BLE temperature/humidity node. It uses a SiWG917 Wi‑Fi/BLE 5.4 module, SHT41 T/RH sensor, USB-C sink input, TPS25940 true reverse-blocking eFuse with OVP/UVLO/OCP/soft-start, MP28301 3.3 V buck regulator, ESD protection, reset/ISP/SWD debug, I2C pull-ups, and status LED.
The schematic is complete with 46 components and 31 nets, including USB-C protection, TPS25940 eFuse, MP28301 buck regulator, SiWG917 Wi‑Fi/BLE module, SHT41 sensor, debug controls, and supporting passives.
Auto-layout could not be run because no ACUs are currently available. Remaining work:
Inspect the existing PCB state to determine whether placement, routing, or both are needed.
Set or verify the board outline and stackup.
Place the SiWG917 at a board edge with its antenna keepout.
Thermally isolate the SHT41 from the MCU, regulator, inductor, and USB-C connector.
Place power and decoupling components close to their associated pins.
Route all nets and resolve airwires and DRC errors.
Assign final passive MPNs before manufacturing export.
Auto-layout is still blocked because no ACUs are available, so I cannot inspect or modify the PCB in this session.
Current state: the 46-component schematic is complete; PCB placement/routing still needs assessment and likely execution, including SiWG917 antenna-edge placement/keepout, SHT41 thermal isolation, power-stage placement, routing, and final DRC.
Technical Construction File — USB-C WiFi BLE TH Sensor
Status
Draft — schematic-stage regulatory file.
Applicable Regulations
FCC Part 15 intentional radiator / unintentional radiator
CE RED for EU radio equipment
ISED Canada if sold in Canada
UKCA if sold in the UK
RoHS/REACH for consumer production
Product Description
USB-C powered indoor consumer temperature/humidity sensor node using a Silicon Labs SiWG917 Wi-Fi/BLE module and Sensirion SHT41 digital T/RH sensor.
Wireless Technology Summary
Table
Module
MPN
Technology
Frequency Band
Antenna
Notes
U1
SIWG917Y111MGABAR
Wi-Fi 2.4 GHz 802.11 b/g/n/ax + BLE 5.4
2.4 GHz ISM
Integrated antenna variant
Must follow Silicon Labs integration/keepout guidance
Required Documentation Checklist
Product block diagram — included in Project Specification
Draft BOM from schematic — available in Flux BOM
RF integration notes — included below
Draft Declaration of Conformity — created in this file
User manual outline — included below
Final schematic PDF export
Final PCB layout/Gerbers after layout
Module certification grants and integration manual from Silicon Labs
EMC/RF test reports from accredited lab
Final product labels with FCC/CE/UKCA marking
RF Design Notes
U1 must be placed at a PCB edge with the integrated antenna facing outward.
Keep the antenna clearance void of copper, traces, vias, components, and metal on all layers.
Keep U3/L1 buck regulator switch node and inductor away from U1 antenna region.
Maintain solid ground under the module body where allowed by the module datasheet.
Do not change the module antenna or add metal/plastic in direct contact with the antenna without RF validation.
Draft Declaration of Conformity
We, [Company Name], declare that the product USB-C WiFi BLE TH Sensor is designed to conform to applicable FCC Part 15, CE RED, RoHS, and EMC requirements when manufactured and integrated according to the final approved schematic, PCB layout, BOM, RF module integration guide, and user manual.